The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC design and materials have produced generations of ICs where the generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased.
As the semiconductor device scaling down continues, challenges in fabrication may arise. For example, scaling down has also increased the risk of bridging or electrical shorting problems, which would degrade semiconductor device performance or even cause device failures. Although existing semiconductor fabrication methods have been generally adequate for their intended purposes, they have not been entirely satisfactory in all respects.